
#include <iostream>

using namespace std;

class stu
{
public:
    stu(string name, int age)
    {
        this->name = name;
        this->age  = age;
    }
    stu & growUp()
    {
        this->age++;
        return *this;
    }
    void display()
    {
        cout<<name<<":"<<age<<endl;
    }

private:
    string name;
    int age;
};

int main(void)
{
    stu lyt("yetin", 24);
    lyt.display();
    
    lyt.growUp().growUp().growUp();
    lyt.display();

    return 0;
}

